Xerographic fuser monitoring apparatus



Dec. 12, 1967 Filed Oct. 11, 1966 XEROGRAPHIC FUSER MONITORING APPARATUS 5 Sheets-Sheet 1 INVENTOR. LARRY M. WOOD A TTOR/VEYS Dec. 12, 1967 L. M. woos 3,357,401

XEROGRAPHIC FUSER MONITORING APPARATUS Filed Oct. 11, 1966 5 Sheets-Sheet 2 INVENTOR. LARRY M. WOOD Dec. 12, 1967 L. M. WOOD 3,357,401

XEROGRAPHIG FUSER MONITORING APPARATUS Filed Oct. 1966 5 Sheets-Sheet 5 120 VOLTS (60-) W m XEROGRAPHIC FIXING APPARATUS LS-l K-l J K4 LS-3 LS-2 1 K-l FEM/MOM: A

H (2) FIRE CONTROL INVENTOR. LARRY M. WOOD A 7'TORNEYS United States Patent Corporation, Rochester, N.Y., a corporation of New York Filed Oct. 11, 1966, Ser. No. 585,972 3 Claims. (Cl. 118-637) This invention relates to xerography and, in particular, to the fixing of resinous xerographic toner powder images to support material.

More specifically, this invention relates to a monitoring apparatus for detecting the presence of support material in an apparatus for fixing resinous toner powder images and to control the operation of the fixing apparatus in accordance with the presence or non-presence of the support material.

In the xerographic process a plate comprising a layer of photoconductive material on a conductive backing is given a uniform electric charge over its surface and then exposed to the subject matter to be reproduced by various projection techniques. This exposure discharges the plate in accordance with the light intensity reaching it thereby creating an electrostatic latent image on or in the plate.

Development of the image is effected by developers which comprise, in general, a mixture of suitable resin based powder, hereinafter referred to as toner, and a carrier material which functions to carry and to generate triboelectric charges on the toner. More specifically, the function of the carrier material is to provide mechanical control of the toner, or to carry the toner to an image surface, and simultaneously provide almost complete homogenity of charge polarity. In the development of the image, toner powder is brought into surface contact with the photoconductive layer and is held thereon electrostatically in a pattern corresponding to the electrostatic latent image. Thereafter, the developed xerographic image may be transferred to a support material to which it may be fixed by any suitable means.

As the science of xerography has progressed faster automatic Xerographic reproducing machines have been developed necessitating improved fixing apparatus capable of fixing the toner powder image to the support material at a rate compatable with the higher speed machines. In fixing the toner powder to the support material it is desired to obtain the highest possible quality of reproduction from the original document and in many applications desirable to obtain a reproduction having a better quality than the original document. Such a fixing apparatus is disclosed in copending application Ser. No. 585,971, filed concurrently herewith on in the names of Gilbert A. Aser et al. and for convenience of illustration the invention of this application will be described with reference to its use therein, although it is not to be limited thereto.

In the apparatus disclosed in the above reference c0- pending application, it is desirable that a sheet of support material passing through the fixing apparatus be closely monitored to detect the clogging of support material inside the fixing apparatus and to control the operation of the fixing apparatus in the event that a sheet of support material would become jammed therein. In such a fixing apparatus, a sheet of support material is electrostatically secured to a transport mechanism for further processing and due, to the minute electrostatic forces securing the support material to the transport mechanism and the intensity of a source of radiant energy utilized with the apparatus, a major problem existed in monitoring sheet material passing through the fixing apparatus.

Due to the low level of electrostatic charge securing the support material to the transport mechanism, a mechanically actuated switch could not be positioned in the path of paper movement to be actuated by contacting the support material. The electrostatic forces securing the support material to the transport mechanism are of such a minute magnitude as to be insutficient to enable the support material to operate a mechanically actuable switch. Thus, the paper would be stripped from the electrostatic transport mechanism and become jammed within the fixing apparatus. In addition, due to the high concentration of radiant energy and the incandescency of the source of radiant energy, a photosensor could not be utilized as a monitoring apparatus even though the problems associated with physical contact of the support material would be eliminated. The magnitude of light intensity from the source of radiant energy would actuate the photosensor at all times regardless of the presence or non-presence of the support material.

The present invention comprises a monitoring apparatus for detecting the presence of support material in an apparatus for fixing resinous toner powder images and actuable to control the fixing apparatus. This invention is unetfected by radiant energy and functions independent of physical contact with the sheet of support material.

It is, therefore, an object of this invention to improve xerographic fixing apparatus of monitoring the support material passing therethrough.

Another object of this invention is to improve monitoring apparatus for use with a xerographic fixing mechanism by eliminating physical contact of the monitoring apparatus with the support material passing through the fixing mechanism.

A further object of this invention is to improve monitoring devices for use with a xerographic fixing apparatus by controlling the operation of the monitoring device ingependently of radiant energy associated with the fixing evice.

Still another object of this invention is to improvexerographic fixing apparatus by the controlling thereof in accordance with a monitoring device uneffected by the operation of the fixing apparatus.

These and other objects are attained in accordance with the present invention wherein there is provided a switch actuable by the pressure of support material and operatively connected with another switch, the operation of which is controlled independently of physical contact with the support material and uneffected by the radiant energy of the fixing device.

Further objects of this invention, together with additional features contributing thereto and advantages accruing therefrom, will be apparent from the following description of one embodiment of the invention when read in conjunction with the accompanying drawings wherein:

FIG. 1 is a front elevation view of an automatic xerograph ic reproducing machine utilizing the invention therein;

FIG. 2 is an enlarged sectional view of the fixing apparatus of the automatic xerographic reproducing machine shown in FIG. 1 to better illustrate the monitoring apparatus;

FIG. 3 is an enlarged horizontal elevation view of the fixing apparatus of FIG. 2 to illustrate the positioning of the monitoring apparatus;

FIG. 4 is an enlarged view of a monitoring switch to better illustrate the parts thereof; and

FIG. 5 is an electrical schematic to illustrate the control circuit of the monitoring apparatus.

Referring now to the drawings, there is shown in FIG. 1 an automatic xerographic reproducing machine having an apparatus for fixing xerographic toner powder images on support material constructed in accordance with the heretofore mentioned copending application Serial No.

3 585,971, filed concurrently herewith on October 11, 1966, in the names of Gilbert A. Aser et al.

Unfused sheet support material bearing a xerographic toner powder image is electrostatically secured to the heated roller 40 to be .directly heated at a constant controllable rate by means of the heat conducted from the roller 40 to the sheet material. As the support material is advanced by means of the roller 40, the toner powder image bearing support material is brought into thermal contact with a source of intense radiant energy whereat the xerographic toner powder image is selectively fixed to the support material; that is, the desired toner powder image is permanently fixed to the support material and the unwanted images are not fixed.

After selectively fixing the toner powder image to the surface of the support material, the support material is removed from the roll by means of a pick-off arm 25 pivotally mounted adjacent to the roller 40 on bracket 27 and engaging a slot provided in the roller. Pivot arm 25 is tapered to a point and positioned so that the point rides below the surface of the roller 40 enabling it to engage the underside of the support material thereby stripping the sheet from the roller. As the support material is stirpped from the roller 40, it engages guide 26 for forwarding to the vacuum sheet transport 60 to be further processed and transported out of the xerographic reproducing machine.

As best shown in FIG. 2, limit switch LS-Z -of the of bracket 27 positioned between the heated roller 40 and the vacuum transport 60 and supported on the machine frame. The limit switch LS2 which may be of any suitable type such as switch E-51 available from Cherry Electric, Highland Park, Illinois, has an actuator arm 23 having a receptor or collector plate 22 secured to one end thereof. The collector 22 is positioned adjacent the path of sheet travel between the heated roller 40 and vacuum transport 60 in cooperative relationship with a source of aeriform fluid emitted through a suitable conduit 20 having an orifice 21 positioned to direct the flow of aeriform fluid onto the collector 22, the aeriform fluid being supplied by means of a compressornot shown.

As seen in the electrical schematic FIG. 5, limit switch LS-3 is a timing switch of the automatic xerographic reproducing machine which is actuable in timed sequence to the forwarding of a sheet of support material into contact with the image of the xerographic drum. The timing switch is periodically actuated as the sheets of support material are forwarded to the xerographic drum. After the image has been transferred from the drum, the support material 'is forwarded by means of the vacuum transport 3i into contact with the heated roller 40 contacting the actuator arm of normally In normal operation the paper is forwarded from the 'heated roller 40 onto the vacuum transport 60 to be discharged from the automatic xerographic reproducing machine, and, therefore, the air stream emitted through the orifice 21 against the collector 22 of limit switch LS-2 will be interrupted due to the support material passing between the orifice and the collector, thereby opening the normally closed contacts of limit switch LS-2. Since the limit switch LS-3 is actuated in timed sequence to the forwarding of sheet support material, the switch is closed once for each sheet passing through the xerographic reproducing machine and this closing occurs at the point in time when a sheet of support material should be passing between the orifice 21 and the collector plate 22, thereby interrupting the impingement of aeriform fluid on the collector plate and allowing switch LS-Z to open.

In normal operation the contacts of relay 'K-l are closed by the support material actuating switch LS-l; the support material will subsequently interrupt the air flow to the collector plate 22 of limit switch LS2 thereby opening the contacts of that switch; and the timing switch LS-3 will be closed in timed sequence to the forwarding of a sheet of support material thus indicating a proper forwarding sequence and holding the power path to relay K-4 open preventing the relay contacts from being actuated to terminate machine operation and actuate a fire control apparatus.

In the event of an occasional jam of support material in the fixing apparatus, contacts K 1 will be closedby the support material actuating switch LS-l; the support material will not emerge from the fixing apparatus to interrupt the air flow from the orifice 21 onto the collector plate 22 of limit switch LS-Z holding theswitch closed; and the timing switch =LS- 3 is closed in timed sequence, to close the power path to relay K-4 to actuate the contacts for terminating the operation of the fixing apparatus and energizing a fire control mechanism to emit for example, carbon dioxide gas into the fixing apparatus.

While there has been shown and described one embodiment of the invention, it is obvious that changes inform could be made without departing from the invention; and it is intended, therefore, that the invention 'be not limited to the exact form shown and described nor to anything less than the whole of the invention'as set forth in theappended claims.

What is claimed is:

1. A monitoring apparatus for sensing the presence of support material in a xerographic fixing apparatus including means for transporting a sheet of support material in a path of movement through a xerographic fixing apparatus,

switch means positioned in said path of movement at the entrance of said xerographic fixing apparatus adapted to be actuated by a sheet of support material,

a source of aeriform fluid positioned adjacent said path of movement at the egress of said xerographic fixing apparatus to direct said aeriform fluid through said path of movement,

switch means positioned at the egress of said xerographic fixing apparatus adjacent said path of movement in cooperative relation with said source of aeriform fluid to be actuated by said aeroform fluid passing through said path of movement, and

means ope-ratively connecting said switching means in an electrical circuit including means to control the operation of said xerographic fixing apparatus upon the operative coincidence of said switchingmeans.

2. The apparatus of claim 1 wherein said switch means ositioned at the egress of said xerographic fixing ap paratus adjacent said path of movement includes a limit switch having a aeriform fluid receptor plate secured to an actuator arm of said swith.

3. The apparatus of claim 2 wherein said switch means positioned at the egress of said xerographic fixing apparatus adjacent said path of movement is normally closed by said source of aeriform fluid impinging upon said receptor plate and opened by the passing of support material moving in said .path of movement to interrupt the impingement of said aeriform fluid upon said receptor plate.

References Cited UNITED STATES PATENTS 2,701,765 2/1955 Codichini et a1. 1'18637 XR 3,053,962 9/1962 Cerasani et al. 219-38 8 3,128,379 4/ 1964 Cisek et al. 25065 3,164,717 1/1965 Kaufman 219-388 3,197,614 7/1965 Engelstad et al. 219-388 3,219,799 11/1965 Trumbull et al. 219388 CHARLES A. WILLMUTH, Primary Examiner.

P. FELDMAN, Assistant Examiner. 

1. A MONITORING APPARATUS FOR SENSING THE PRESENCE OF SUPPORT MATERIAL IN A XEROGRAPHIC FIXING APPARATUS INCLUDING MEANS FOR TRANSPORTING A SHEET OF SUPPORT MATERIAL IN A PATH OF MOVEMENT THROUGH A XEROGRAHIC FIXING APPARATUS, SWITCH MEANS POSITIONED IN SAID PATH OF MOVEMENT AT THE ENTRANCE OF SAID XEROGRAPHIC FIXING APPARATUS ADAPTED TO BE ACTUATED BY A SHEET OF SUPPORT MATERIAL, A SOURCE OF AERIFORM FLUID POSITIONED ADJACENT SAID PATH OF MOVEMENT AT THE EGRESS OF SAID XEROGRAPHIC FIXING APPARATUS TO DIRECT SAID AERIFORM FLUID THROUGH SAID PATH OF MOVEMENT, SWITCH MEANS POSITIONED AT THE EGRESS OF SAID XEROGRAPHIC FIXING APPARATUS ADJACENT SAID PATH OF MOVEMENT IN COOPERATIVE RELATION WITH SAID SOURCE OF AERIFORM FLUID TO BE ACTUATED BY SAID AEROFORM FLUID PASSING THROUGH SAID PATH OF MOVEMENT, AND MEANS OPERATIVELY CONNECTING SAID SWITCHING MEANS IN AN ELECTRICAL CIRCUIT INCLUDING MEANS TO CONTROL THE OPERATION OF SAID XEROGRAPHIC FIXING APPARATUS UPON THE OPERATIVE COINCIDENCE OF SAID SWITCHING MEANS. 